1. Field of Invention
The present invention relates to a semiconductor structure and a manufacturing method of the semiconductor structure.
2. Description of Related Art
In manufacturing a semiconductor structure of an image sensor, a light transmissive sheet is often arranged on a surface of a wafer, and the light transmissive sheet and the wafer are spaced apart at a distance with a dam element. Thereafter, a V-shaped trench is formed in the wafer by etching.
After the trench is formed, photoresist is used to cover the surface of the wafer facing away from the light transmissive sheet. A portion of the photoresist enters the trench due to the gravity to cover the sidewall of the wafer facing the trench. Afterwards, a portion of the photoresist in the trench and a portion of the dam element under the photoresist are removed by exposure and etching processes. As a result, the photoresist left on the sidewall may be regarded as an isolation layer. Subsequently, a conductive layer can be formed on the isolation layer, so as to be electrically connected to the conductive pad of the wafer.
However, in the typical manufacture of the semiconductor structure, only a single photoresist is used to fill the trench. When the photoresist in the trench is etched, the thickness of the photoresist on the turning point of the wafer adjacent to the trench may become too small to provide desired stress or thickness after applying the conductive layer overlying the photoresist, and thus the reliability of the semiconductor structure is reduced. That is to say, in the manufacture of the typical semiconductor structure it is not easy to control the thickness of the isolation layer, and to flexibly adjust the stress of the isolation layer.